The present invention relates to a centrifugal separator capable of obviating erroneous use, inclusive of erroneous setting, of a rotor and also relates to a rotor of the centrifugal separator.
FIG. 5 is an illustrated sectional view of an essential portion including a rotor of a centrifugal separator having a conventional structure, and a left-half thereof shows a state that buckets (non-usable buckets) having a large capacity (volume) are swung by a centrifugal force and a right-half thereof shows buckets (usable buckets) having a small capacity are swung by a centrifugal force.
The centrifugal separator comprises a drive unit D, a driving shaft 11 driven and rotated by the drive unit, a crown 4 as a power transmission mounted to a front end of the driving shaft 11 and having a crown pin 6a, a swing rotor 1 having a hole 8 into which a crown 4 is inserted and formed with a pin 6b to be engaged with the pin 6a, a rotor chamber (casing) 10 into which the rotor 1 is accommodated and a cover 12 covering an opening between the rotor casing 10 and the driving shaft 11. A door, not shown, may be further provided for opening or closing an upper opening of the rotor casing 10 through which the swing rotor 1 is inserted into or taken out from the rotor casing 10.
Rotors for holding samples generally include a vertical rotors, angle rotors, swing rotors and so on, and the swing rotor is different from the other type rotors. The swing rotor 1 is provided with a rotor body 2, an arm 9 provided for the rotor body 2 and a plurality of buckets 3 arranged to the arm 9 so that the buckets 3 are swingable in the centrifugal direction with the arm 9 being the swing rotation center thereof.
In order to treat a lot of samples at one time by using a swing rotor, it will be necessary to make large the bucket, in size, for holding the sample and also necessary to design the rotor chamber, into which the rotor is accommodated, so as to have an inner diameter D3 larger than the maximum rotating diameter D2 of the swing rotor at a time when the bucket is swung from the vertical direction towards the horizontal direction (i.e. the diameter D2 of the swing rotor at the time of being rotated at the maximum rotating rate).
In general, the separation of the sample is performed by using a swing rotor which was preliminarily selected so as to conform with the inner diameter of the rotor casing. However, in some occasion, this swing rotor is to be exchanged with another swing rotor in accordance with its use or object. In such case, however, a swing rotor having the maximum rotating diameter D2 larger than the inner diameter D3 of the rotor casing 10 can be accommodated because the maximum outer diameter D1 of the swing rotor at the operation stopping time (not driving time) is smaller than the inner diameter D3 of the rotor casing 10. In such state, when an operator operates the swing rotor 1 without acknowledging this selection error of the swing rotor (erroneous setting), the buckets are being swung by the centrifugal force will contact the inside wall section having the inner diameter D3 of the rotor casing 10 smaller than the maximum rotating diameter D2 of the swing rotor 1, thus damaging the rotor, loosing the sample, and hence, damaging the centrifugal separator itself, hence being defective.
An object of the present invention is to substantially eliminate defects or drawbacks encountered in the prior art mentioned above and to provide a centrifugal separator capable of safely achieving an improved working efficiency with less setting error of the rotor.
Another object of the present invention is to also provide a rotor of the centrifugal separator of the character mentioned above which is superior in safe operation and operational reliability.
These and other objects can be achieved according to the present invention by providing, in one aspect, a centrifugal separator comprising:
a driving unit;
a power transmission unit including a driving shaft operatively connected to the driving unit to be rotatable and a crown mounted to one end of the driving shaft;
a rotor having a rotor body to which an insertion hole into which the crown is inserted is formed and including a sample holding member, the rotor being formed with a projection member so as to extend outward;
a rotor casing into which the rotor is accommodated in a rotatable manner; and
a receiving member disposed on the rotor casing side and adapted to receive the projection member,
wherein, in a state that the crown is inserted into the insertion hole from a bottom wall side of the rotor casing, a first distance between the bottom wall of the rotor casing and a front end portion of the crown is made smaller than a second distance between a bottom portion of the projection member and a bottom portion of the insertion hole formed to the rotor body and wherein the receiving member is formed as an annular recess, i.e. groove, the annular recess having a depth larger than a difference between the second distance and the first distance.
The receiving member is an annular recess and the projection member is an annular projection, or comprises a plurality of projection pins, having a center arranged on a rotational axis of the driving shaft.
The rotor casing is formed with an opening through which the driving shaft extends into the rotor casing, a cover is disposed so as to cover the opening, and the receiving member is formed to the cover.
The rotor is a swing rotor and the sample holding member comprises a plurality of buckets. The rotor body of the swing rotor is formed with cutouts into which downward end portions of the buckets are received, respectively, at a time when the swing rotor is stopped in operation.
In a further aspect of the present invention, there is provided a rotor to be accommodated in a rotor casing comprising:
a rotor body having a rotational axis about which the rotor body is rotated and having an insertion hole into which a power transmission member for rotating the rotor body is fitted, the rotor body being formed with a projection member which is received in a receiving member formed to the rotor casing side; and
a plurality of sample holding members arranged on a circumferential portion with the rotational axis being the center thereof,
wherein, in a state that the crown is inserted into the insertion hole from a bottom wall side of the rotor casing, a first distance between the bottom wall of the rotor casing and a front end portion of the power transmission member is made smaller than a second distance between a bottom portion of the projection member and a bottom portion of the insertion hole formed to the rotor body.
In preferred examples of this aspect, the projection member is an annular projection having a center arranged on a rotational axis of the power transmission member. The projection member may comprise a plurality of projection pins arranged in an annular shape having a center arranged on a rotational axis of the power transmission member.
The rotor is a swing rotor and the sample holding member comprises a plurality of buckets. The rotor body of the swing rotor is formed with cutouts into which downward end portions of the buckets are received, respectively, at a time when the swing rotor is stopped in operation.
According to the centrifugal separator and the rotor thereof of the characters mentioned above, the setting errors of the rotor, particularly, swing rotor, can be substantially eliminated by the specific location of the annular projection member formed to the rotor body and the annular groove for receiving the projections, and therefore, the working efficiency of the centrifugal separator can be improved, thus being safe and advantageous.
Furthermore, the safeness and reliability, in operation, rotor can be also provided.
Still furthermore, in a preferred aspect, the swing rotor having the maximum rotating diameter larger than the inner diameter of the rotor casing into which the swing rotor is accommodated cannot be mounted in a rotatable manner, and moreover, the swing rotor of the present invention can be rotated by using a centrifugal separator specific to such swing rotor. Therefore, the safeness and reliability for the operation of the centrifugal separator can be ensured.
The nature and further characteristic features of the present invention will be made more clear from the following descriptions made with reference to the accompanying drawings.